/**
 * Copyright (c) 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule DraftModifier
 * @format
 * @flow
 */

'use strict';

import type { BlockMap } from './BlockMap';
import type ContentState from './ContentState';
import type { DraftBlockType } from './DraftBlockType';
import type { DraftInlineStyle } from './DraftInlineStyle';
import type { DraftRemovalDirection } from './DraftRemovalDirection';
import type SelectionState from './SelectionState';
import type { Map } from 'immutable';

var CharacterMetadata = require('./CharacterMetadata');
var ContentStateInlineStyle = require('./ContentStateInlineStyle');
const DraftFeatureFlags = require('./DraftFeatureFlags');
var Immutable = require('immutable');

var applyEntityToContentState = require('./applyEntityToContentState');
var getCharacterRemovalRange = require('./getCharacterRemovalRange');
var getContentStateFragment = require('./getContentStateFragment');
var insertFragmentIntoContentState = require('./insertFragmentIntoContentState');
var insertTextIntoContentState = require('./insertTextIntoContentState');
var invariant = require('fbjs/lib/invariant');
var modifyBlockForContentState = require('./modifyBlockForContentState');
var removeEntitiesAtEdges = require('./removeEntitiesAtEdges');
var removeRangeFromContentState = require('./removeRangeFromContentState');
var splitBlockInContentState = require('./splitBlockInContentState');

const { OrderedSet } = Immutable;

/**
 * `DraftModifier` provides a set of convenience methods that apply
 * modifications to a `ContentState` object based on a target `SelectionState`.
 *
 * Any change to a `ContentState` should be decomposable into a series of
 * transaction functions that apply the required changes and return output
 * `ContentState` objects.
 *
 * These functions encapsulate some of the most common transaction sequences.
 */
var DraftModifier = {
  replaceText: function (contentState: ContentState, rangeToReplace: SelectionState, text: string, inlineStyle?: DraftInlineStyle, entityKey?: ?string): ContentState {
    var withoutEntities = removeEntitiesAtEdges(contentState, rangeToReplace);
    var withoutText = removeRangeFromContentState(withoutEntities, rangeToReplace);

    var character = CharacterMetadata.create({
      style: inlineStyle || OrderedSet(),
      entity: entityKey || null
    });

    return insertTextIntoContentState(withoutText, withoutText.getSelectionAfter(), text, character);
  },

  insertText: function (contentState: ContentState, targetRange: SelectionState, text: string, inlineStyle?: DraftInlineStyle, entityKey?: ?string): ContentState {
    invariant(targetRange.isCollapsed(), 'Target range must be collapsed for `insertText`.');
    return DraftModifier.replaceText(contentState, targetRange, text, inlineStyle, entityKey);
  },

  moveText: function (contentState: ContentState, removalRange: SelectionState, targetRange: SelectionState): ContentState {
    var movedFragment = getContentStateFragment(contentState, removalRange);

    var afterRemoval = DraftModifier.removeRange(contentState, removalRange, 'backward');

    return DraftModifier.replaceWithFragment(afterRemoval, targetRange, movedFragment);
  },

  replaceWithFragment: function (contentState: ContentState, targetRange: SelectionState, fragment: BlockMap): ContentState {
    var withoutEntities = removeEntitiesAtEdges(contentState, targetRange);
    var withoutText = removeRangeFromContentState(withoutEntities, targetRange);

    return insertFragmentIntoContentState(withoutText, withoutText.getSelectionAfter(), fragment);
  },

  removeRange: function (contentState: ContentState, rangeToRemove: SelectionState, removalDirection: DraftRemovalDirection): ContentState {
    let startKey, endKey, startBlock, endBlock;
    if (rangeToRemove.getIsBackward()) {
      rangeToRemove = rangeToRemove.merge({
        anchorKey: rangeToRemove.getFocusKey(),
        anchorOffset: rangeToRemove.getFocusOffset(),
        focusKey: rangeToRemove.getAnchorKey(),
        focusOffset: rangeToRemove.getAnchorOffset(),
        isBackward: false
      });
    }
    startKey = rangeToRemove.getAnchorKey();
    endKey = rangeToRemove.getFocusKey();
    startBlock = contentState.getBlockForKey(startKey);
    endBlock = contentState.getBlockForKey(endKey);
    const startOffset = rangeToRemove.getStartOffset();
    const endOffset = rangeToRemove.getEndOffset();

    const startEntityKey = startBlock.getEntityAt(startOffset);
    const endEntityKey = endBlock.getEntityAt(endOffset - 1);

    // Check whether the selection state overlaps with a single entity.
    // If so, try to remove the appropriate substring of the entity text.
    if (startKey === endKey) {
      if (startEntityKey && startEntityKey === endEntityKey) {
        const adjustedRemovalRange = getCharacterRemovalRange(contentState.getEntityMap(), startBlock, endBlock, rangeToRemove, removalDirection);
        return removeRangeFromContentState(contentState, adjustedRemovalRange);
      }
    }
    let adjustedRemovalRange = rangeToRemove;
    if (DraftFeatureFlags.draft_segmented_entities_behavior) {
      // Adjust the selection to properly delete segemented and immutable
      // entities
      adjustedRemovalRange = getCharacterRemovalRange(contentState.getEntityMap(), startBlock, endBlock, rangeToRemove, removalDirection);
    }

    var withoutEntities = removeEntitiesAtEdges(contentState, adjustedRemovalRange);
    return removeRangeFromContentState(withoutEntities, adjustedRemovalRange);
  },

  splitBlock: function (contentState: ContentState, selectionState: SelectionState): ContentState {
    var withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
    var withoutText = removeRangeFromContentState(withoutEntities, selectionState);

    return splitBlockInContentState(withoutText, withoutText.getSelectionAfter());
  },

  applyInlineStyle: function (contentState: ContentState, selectionState: SelectionState, inlineStyle: string): ContentState {
    return ContentStateInlineStyle.add(contentState, selectionState, inlineStyle);
  },

  removeInlineStyle: function (contentState: ContentState, selectionState: SelectionState, inlineStyle: string): ContentState {
    return ContentStateInlineStyle.remove(contentState, selectionState, inlineStyle);
  },

  setBlockType: function (contentState: ContentState, selectionState: SelectionState, blockType: DraftBlockType): ContentState {
    return modifyBlockForContentState(contentState, selectionState, block => block.merge({ type: blockType, depth: 0 }));
  },

  setBlockData: function (contentState: ContentState, selectionState: SelectionState, blockData: Map<any, any>): ContentState {
    return modifyBlockForContentState(contentState, selectionState, block => block.merge({ data: blockData }));
  },

  mergeBlockData: function (contentState: ContentState, selectionState: SelectionState, blockData: Map<any, any>): ContentState {
    return modifyBlockForContentState(contentState, selectionState, block => block.merge({ data: block.getData().merge(blockData) }));
  },

  applyEntity: function (contentState: ContentState, selectionState: SelectionState, entityKey: ?string): ContentState {
    var withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
    return applyEntityToContentState(withoutEntities, selectionState, entityKey);
  }
};

module.exports = DraftModifier;